Re: [Matplotlib-users] incorrect boxplot?

[Robert K. <rob...@gm...>]

On 2009-09-14 16:08 PM, Gökhan Sever wrote:
>
>
> On Mon, Sep 14, 2009 at 3:45 PM, <jas...@cr...
> <mailto:jas...@cr...>> wrote:
>
>     Robert Kern wrote:
>      > prctile does not handle the case where the exact percentile lies
>     between two
>      > items. scoreatpercentile does.
>      >
>      >
>
>     If mlab is supposed to be compatible with matlab, then isn't this a
>     problem?
>
>       From matlab, version 7.2.0.283 (R2006a)
>
>      >> prctile([1 1 2 2 1 2 4 3 2 2 2 3 4 5 6 7 8 9 7 6 4 5 5],[0 25 50 75
>     100])
>
>     ans =
>
>         1.0000    2.0000    4.0000    5.7500    9.0000
>
>
>     Of course, the 75th percentile is different here too (5.75 instead of
>     scipy's 5.5).  I don't know how to explain that discrepancy.
>
>     Jason
>
>
> Now there are 3 different 75 percentiles :). Any ideas, which is one the
> most correct?

They are all reasonable. There are lots of different ways of handling this case. 
 From the R documentation:

http://sekhon.berkeley.edu/stats/html/quantile.html

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco